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Constraining hillslope sediment flux using high resolution topographic data

Constraining hillslope sediment flux using high resolution topographic data. Stuart Grieve, Simon Mudd & Martin Hurst. What is hillslope sediment flux?. Volume of sediment transported on a hillslope per unit area in a period of time Integral in landscape evolution modelling.

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Constraining hillslope sediment flux using high resolution topographic data

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  1. Constraining hillslope sediment flux using high resolution topographic data Stuart Grieve, Simon Mudd& Martin Hurst

  2. What is hillslope sediment flux? • Volume of sediment transported on a hillslope per unit area in a period of time • Integral in landscape evolution modelling • Sediment flux controls: • Geometry of hillslopes • Landscape response to climate and tectonic forcing

  3. What is hillslope sediment flux? • Creep dominated landscapes • High infiltration capacity

  4. What is hillslope sediment flux? • Two end-member models of sediment flux:

  5. Constraining linear flux • Mckean (1993) • Small (1999) • Cosmogenic radionuclides

  6. Constraining nonlinear flux • Howard (1994) • Basin modelling • Roering (1999,2001) • CRN & basin measurements • Analogue hillslopes

  7. Constraining sediment flux • Limited to local scale • Can we constrain hillslope sediment flux at a landscape scale? • Both models make predictions about relief structure of landscapes

  8. Predicted relief structure

  9. Predicted relief structure: Linear • Steady state hillslope • Uplifted at 0.1, 0.2 & 0.3 mm/yr

  10. Predicted relief structure: Nonlinear • Steady state hillslope • Uplifted at 0.1, 0.2 & 0.3 mm/yr

  11. Dimensionless relief and curvature Oregon Coast Range Gabilan Mesa

  12. Topographic analysis • Challenge is to move beyond basin scale • We need to measure some parameters continuously across our landscapes: • Hillslope length • Relief • Hilltop curvature

  13. Connecting hillslopes to channels • Model sediment flow from hilltop to channel • Couples every hillslope to it’s channel

  14. Measuring hillslopes directly • Don’t use steepest descent • Model flow within each pixel • Gives a more realistic flow path on hillslopes 100 150 20 280 170 70 120 350 90

  15. Relief and hilltop curvature

  16. Measuring hillslopes directly • We have continuous measurements of these values across our landscapes 72 m 57 m

  17. Measuring hillslopes directly 39 m 37 m

  18. Measuring hillslopes directly 0.014 m-1 0.07 m-1

  19. Hillslope length-relief relationships

  20. Dimensionless relief and curvature

  21. Conclusions • Strong evidence for nonlinear sediment flux at a landscape scale • Dimensionless parameters show more variation than expected for steady state landscapes

  22. LSDTopoTools • Interested in trying this software out? • Poster P-S1

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